Grinding induced effects in plasma sprayed zirconia coatings

The effect of grinding on the surface layer properties of ceria and yttria partially stabilized zirconia plasma-sprayed coatings (CePSZ, YPSZ, respectively) has been studied by X-ray diffraction methods. For this purpose, the modified model of line broadening analysis has been derived. The model considers elastic anisotropic properties along with more random paracrystal imperfections, both affecting X-ray line broadening. Grinding-induced microstructural changes were also studied using an estimation from the quantitative Orientation Distribution Function (ODF) texture. It was concluded, based on this work, that CePSZ ceramic is less mechanically stable compared to YPSZ. Consequently, more beneficial mechanical properties of a ground surface layer can be expected for CePSZ plasma-sprayed coatings.     

基于图像处理的叶面积测量方法

采用数字图像处理方法对毛白杨叶片进行长、宽、面积的测算,并应用Hough变换对叶片畸变图像进行校正,取得了可靠的数据,建立了叶片长、宽、长宽乘积和面积的回归方程,结果有着显著的相关性,为植物叶面积快速估算提供了一条比较好的途径.     

智能材料和智能结构——形状记忆材料

研究了形状记忆材料,如形状记忆合金、陶瓷和聚合物的结构、生产方法、特性和应用。形状记忆材料具有许多优秀的智能特性,例如传感（热、应力和场）、大行程执行器、高阻尼、自适应响应、形状记忆、超弹性等,可用于各种智能系统。形状记忆材料中的激励感应相变导致了材料的许多独特的性能,支配着材料性质的显著变化。讨论了改进目前材料系统和研发新的形状记忆材料所面临的技术障碍和挑战。     

A multi-scale template method for shape detection with bio-medical applications

In this paper we present a novel methodology based on non-parametric deformable prototype templates for reconstructing the outline of a shape from a degraded image. Our method is versatile and fast and has the potential to provide an automatic procedure for classifying pathologies. We test our approach on synthetic and real data from a variety of medical and biological applications. In these studies it is important to reconstruct accurately the shape of the object under investigation from very noisy data. Here we assume that we have some prior knowledge about the object outline represented by a prototype shape. Our procedure deforms this shape by means of non-affine transformations and the contour is reconstructed by minimizing a newly developed objective function that depends on the transformation parameters. We introduce an iterative template deformation procedure in which the scale of the deformation decreases as the algorithm proceeds. We compare our results with those from a Gaussian Mixture Model segmentation and two state-of-the-art Level Set methods. This comparison shows that the proposed procedure performs consistently well on both real and simulated data. As a by-product we develop a new filter that recovers the connectivity of a shape.

Continuity versus Discretization

The threefold interest in architecture, biology and mathematics motivated us to examine and justify new architectural forms. We discuss some notions of rhythm: Euclidean, morphogenetic and morphologic. Contemporary relationships between structure and form are based on the generation of shape by technological processes, thus the resulting objects are restricted to their material expression. Here a phenomenological organisation of form and its continuity with the landscape arise out of the mathematical and architectural creativity. The use of the computer is applied from outside to inside instead from inside to outside; this means that we are dealing with the organisational processes via continuous methods instead of evolutionary processes given by computer simulations, known as genetic algorithms, where the resulting configurations are reduced to a matter of routine. The role of design as an aesthetic component innovates the theoretical framework of structural engineering to establish the architectural environments.     

作物残体去向与利用及对土壤氮素转化的影响

近年来,作物残体还田受到了很大的关注,一方面它可以改进土壤氮素的动态变化,减少硝态氮淋失;另一方面可作为提高耕地土壤作为潜在氮储库的一种手段。作物残体是碳、氮的重要源和库,因此还田后会影响土壤中的氮素循环。本文综述了作物残体还田后对土壤氮素转化的影响及残体氮素的利用与去向问题。具体阐述了以下几个方面内容:作物残体的降解过程及影响因素,残体氮素的利用率及去向问题,以及作物残体对土壤无机氮库、有机氮库、微生物特征的影响。     

Application of the general elimination method in robot kinematics

A general method for solving the robot inverse kinematics problem is presented. The method is based upon the general elimination method to obtain the equivalent system of equations which are triangularized and the solutions of the inverse kinematics problem can be solved by backsubstitutions.     

A Novel Magnetic Hardening Mechanism for Nd-Fe-B Permanent Magnets Based on Solid-State Phase Transformation

Permanent magnets based on neodymium-iron-boron (Nd-Fe-B) alloys provide the highest performance and energy density, finding usage in many high-tech applications. Their magnetic performance relies on the intrinsic properties of the hard-magnetic Nd₂Fe₁₄B phase combined with control over the microstructure during production. In this study, a novel magnetic hardening mechanism is described in such materials based on a solid-state phase transformation. Using modified Nd-Fe-B alloys of the type Nd₁₆Fe_bal-x-y-zCo_xMo_yCu_zB₇ for the first time it is revealed how the microstructural transformation from the metastable Nd₂Fe₁₇B_x phase to the hard-magnetic Nd₂Fe₁₄B phase can be thermally controlled, leading to an astonishing increase in coercivity from ≈200 kAm⁻¹ to almost 700 kAm⁻¹. Furthermore, after thermally treating a quenched sample of Nd₁₆Fe₅₆Co₂₀Mo₂Cu₂B₇, the presence of Mo leads to the formation of fine FeMo₂B₂ precipitates, in the range from micrometers down to a few nanometers. These precipitates are responsible for the refinement of the Nd₂Fe₁₄B grains and so for the high coercivity. This mechanism can be incorporated into existing manufacturing processes and can prove to be applicable to novel fabrication routes for Nd-Fe-B magnets, such as additive manufacturing.     

Microstructure,Phase Composition,and Thermal Stability of Two Zirconium Alloys Subjected to High‐Pressure Torsion at Different Temperatures

The structure, phase composition, and thermal stability of the industrial zirconium alloys, namely, E110 (Zr–1% Nb) and E635 (Zr–1% Nb–0.3% Fe–1.2% Sn), which are subjected to high‐pressure torsion (HPT) at room temperature (RT), 200, and 400 °С have been studied. HPT of Zr‐alloys at RT (10 revolutions) leads to the formation of grain–subgrain nano‐sized structure and to increase the microhardness by 2.1…2.8 times. The increase in the HPT temperature to 200–400 °С leads to the increase in the structural‐element average size. The structural‐element size in the complexly alloyed E635 alloy in all cases is lower compared with the E110 alloy. The hardening of the alloys after HPT at RT and 200 °С is close, and at 400 °С is much less. HPT initiates the α‐Zr → (ω‐Zr + β‐Zr) transformation, which is the main factor for alloys hardening. The α‐Zr → (ω‐Zr + β‐Zr) transformation in the E635 alloy occurs less quickly. The maximum amount (ω‐Zr + β‐Zr) phase in the structure of the alloys is observed after HPT at RT and 200 °C, and the minimum ? at 400 °C. During heating, the alloys undergo the reverse (ω‐Zr + β‐Zr) → α transformation which depends on both the alloy composition and HPT temperature.

     

可拉伸为任意多边形的自由拉伸算法

针对图像特殊变换问题,即把一个N（N〉3）边形的图像变换为另一个M（M〉N）边形的图像的变形,提出了一种自由拉伸的算法。在该算法的基础上进行适当的变换,不仅能实现基本的几何变换,如缩放、错切、扭曲等,还可以实现N边形的图像变换为半圆或者为N边形（边为曲线）的图像等复杂的图像变换。实验证明该算法取得了很好的效果[1]。